Chlorophyll accumulation rate

Fig. 5. The rate of chlorophyll accumulation in etiolated seedlings exposed to continuous light for 5 d. Wild type, lut2, abal and Iul2aba I etiolated tissue culture-grown seedlings were vernalized, germinated in the dark for 3 d and then transferred to continuous light. At each time point, 2 replicate extracts of 10 pooled seedlings were analyzed and the chlorophyll content expressed on a per plant basis (pg/seedling). Standard deviations greater than the size of the symbol are shown.

Fargasova, A. (1998). Accumulation and toxic effects of Cu2+, Cu+, Mn2+, VC>4, Ni2+ and M0O4- and their associations influence on respiratory rate and chlorophyll a content of the green alga Scenedesmus quadricauda, J. Trace Micro. Tech., 16, 481-490. 

Phenolic acids are known to alter photosynthetic and respiration rates, cause stomatal closure, reduce chlorophyll content, modify the flow of carbon into various metabolic pools, and alter nutrient uptake in affected tissue (61-73). A common denominator for these multiple effects appears to be the action of phenolic compounds on membranes. They are soluble in membranes, and cause a reduction in ion accumulation in cells (71-73). Several phenolic acids cause membrane depolarization, especially at low pH, increasing membrane permeability to ions (72,73). This action undoubtedly impairs the proton gradient and ATP-driven ion transport. Logically, the effects phenolic acids have on membranes could disturb the water balance and mineral nutrition of seedlings, and research in my laboratory has established such a relationship. 

Iron is an essential nutrient for all living organisms, fron is required for the synthesis of chlorophyll and of several photosynthetic electron transport proteins and for the reduction of CO2, SO , and NOj" during the photosynthetic production of organic compounds. Iron concentrations in vast areas of the ocean are very low (< 1 nM) due to the low solubihty of iron in oxic seawater. Low iron concentrations have been shown to limit primary production rates, biomass accumulation, and ecosystem stmcture in a variety of open-ocean environments, including the equatorial Pacific, the subarctic Pacific and the Southern Ocean and even in some coastal areas. 

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